Relive Hailey Upton's Incredible Evolution on Chicago P.D.

Chicago P.D. fans first met Upton in Season 4, Episode 21 (“Fagin”), after she collaborated with the Intelligence Unit as a detective for CPD's Robbery-Homicide Unit. Upton was irritated that  Intelligence had swooped in on her case but, after combining brains with Sergeant Hank Voight (Jason Beghe) and Halstead, she learned she worked well with the investigators.

By the episode's end, Voight had offered Upton a job within his unit, which she accepted in the following episode ("Army of One"). 

Upton was determined to prove herself within the CPD, often becoming the first officer to throw herself into a case or prioritize an investigation over her personal life. Upton's policing style is defined by empathy and calculated vulnerability— she's privy to spinning stories to coax confessions but always makes room for survivor testimony — and her tumultuous childhood strengthened her skill in identifying abuse risk factors, which paved the way for dozens of arrests.

Her toxic upbringing also meant Upton had spent significant time at the CPD as a young girl, which is how she first met the tough-as-nails Trudy Platt (Amy Morton). Spending time with Trudy eventually inspired Upton to become a cop — and, while typically stoic, Trudy couldn't help but get emotional after meeting Upton as an adult and witnessing how far she'd come.

Throughout Season 7 of Chicago P.D., Halstead and Upton's partnership evolved into a swoon-worthy romance. Then, after Halstead was shot in Season 7, Episode 10 ("Mercy), Upton refused to leave his side at the hospital. As her colleagues took note of her steadfast attendance, Upton admitted she loved him as a partner, the first sign of her deeper feelings. (Halstead was, of course, equally devoted to Upton.)

By Season 8 of Chicago P.D., the partners had gone through everything from attempted kidnappings to being framed for murder, but they stuck together. However, after Upton received a job offer from the feds in New York City, she was forced to consider her future. 

RELATED: A Look Back at Halstead and Upton's Slow-Burn Romance on Chicago P.D.

In Season 8, Episode 3 ("Tender Age"), Upton told Halstead she wasn't taking the job because she belonged in Chicago with him. After she admitted that it had been a long time since she'd viewed him as "just her partner," the two kissed for the first time. The couple's relationship quickly blossomed, and while they kept it professional on the job, Voight eventually learned of their relationship after the couple shared their first "I love you"s. 

In the Season 8 finale —after Upton became traumatized when she accidentally killed a suspect involved in the kidnapping of her colleague Kim Burgess (Marina Squerciati) — Upton proposed to Halstead, telling him she always wanted him in her life, an offer he was blindsided by. 

In the Season 9 premiere ("Closure"), the partners were forced to table their proposal conversation to address the fallout from the rest of the Season 8 finale. Halstead eventually asked Upton why she proposed, scanning for her logic. Upton confessed she craved stability and trusted she'd always be happy with Halstead at the end of their respective stressful days, as he'd always been her anchor. 

RELATED: These Are The Most Beloved Couples on Chicago Fire, Med, and P.D.

Halstead then surprised Upton by asking her to marry him, admitting that he'd known for years that they were meant to be together.

The pair moved in together in Season 9, Episode 3 ("The One Next to Me") and broke the news of their engagement to the rest of the Intelligence Unit shortly after.

Halstead eventually decided that he wanted to get married as soon as possible to not waste any precious time together, and the two eloped for a confidential courthouse wedding in Season 9, Episode 9 ("A Way Out").

In Season 6 of Chicago P.D., Upton had a brief fling with Intelligence Unit Detective Adam Ruzek (Patrick John Flueger). The pair met working together on a few cases, where it became instantly clear that Upton and Ruzek approached investigations very differently. Ruzek's hallmark aggression and bluntness with suspects rubbed Upton the wrong way, and he failed to understand her methodical tactics with suspects. In many ways, Upton and Ruzek neutralized each other but eventually grew close as friends. 

Upton and Ruzek then became more than friends in Season 6, Episode 6 ("Bad Boys") after Halstead was shot during a particularly rough case. Halstead recovered, but Ruzek was there for Upton during the high-stress fallout. After the pair woke up together after a one-night stand, they began exploring their feelings for each other to see where their relationship could go. They agreed to keep their relationship on the down-low but, considering they were surrounded by Intelligence officers, the jig was up fairly quickly. 

RELATED: What to Know About Burgess and Ruzek's Chicago P.D. Romance

Their colleagues' knowledge of the once-secret romantic relationship escalated some of the issues already present within the couple's interactions on the job. Upton fundamentally disagreed with Ruzek's policing style and aggression issues, while their status as coworkers consistently chipped away at their relationship. Ruzek and Upton broke up in Season 6, Episode 12 ("Sacrifice"), but Ruzek was keen to comment that their ending was more complicated than simple workplace drama — implying that she harbored feelings for Halstead while he still carried a torch for Burgess.

Ruzek and Upton ultimately worked better together as friends and have remained close since.

While Upton historically keeps her policing as straight edge as possible, she took a darker outlook on the job in Season 7 of Chicago P.D. after she orchestrated the death of a man who murdered one of her valued informants. The king of a cover-up, Voight sniffed out Upton's erratic behavior and sent her to New York City's FBI office for a few weeks to fill in for an undercover agent.

Voight hoped the time away from Chicago would help Upton come to her senses, leading to her guest appearance on Dick Wolf's FBI Season 2, Episode 19. ("Emotional Rescue"). Surrounded by straight-laced investigators, Upton quickly learned dirty policing is never the route to a clean arrest. Upton returned to the Windy City during the Chicago P.D. Season 8 premiere ("Fighting Ghosts"). 

Just as the Upstead flag began to fly high following their Season 9 wedding, fate had other plans. As Halstead's often-immoral police tactics began to catch up with him, he became increasingly unhappy with his job in the Intelligence Unit. He ultimately resigned from his post in Season 10, Episode 3 ("The Great Man") and accepted a job with the army to hunt down drug cartels in Bolivia. The news was devastating to Upton, who watched her husband leave Chicago with just a day's notice.

RELATED: Jesse Lee Soffer Finally Reveals Why He Left Chicago P.D.

"It's not forever, it's eight months, maybe a little longer," Halstead told Upton before leaving. "But I swear to you that we're gonna get through this because you're the love of my life, and if I'm yours, then you'll know that you have to let me go."

Upton was heartbroken but chose to support her husband. Still, the distance began taking a toll on their marriage once Upton realized Halstead's job prevented him from calling or texting her. After she called Halstead's boss in Season 10, Episode 12 ("I Can Let You Go"), Upton was saddened to learn that her husband had extended his tour in Bolivia without notifying her. 

Upton attempted to bury her grief beneath her intense workload, but her anger toward Halstead reached a fever pitch in Season 10, Episode 20 ("Fight"). After Upton survived a horrific kidnapping in an attempt to save one of Halstead's former informants, she was forced to confront the fact that her husband would never have noticed her missing because he wasn't there.

After she survived, the grim reality of their relationship set in and, after tearfully gazing at pictures and keepsakes in the couple's home, Upton took off her wedding ring. 

Upton and Halstead are apparently finished — but Chi-Hards are perched to find out what Upton does next in Season 11 of Chicago P.D.